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/*
 *  streams library
 *
 *  Copyright (C) 2011-2012 by Christian Bockermann, Hendrik Blom
 * 
 *  streams is a library, API and runtime environment for processing high
 *  volume data streams. It is composed of three submodules "stream-api",
 *  "stream-core" and "stream-runtime".
 *
 *  The streams library (and its submodules) is free software: you can 
 *  redistribute it and/or modify it under the terms of the 
 *  GNU Affero General Public License as published by the Free Software 
 *  Foundation, either version 3 of the License, or (at your option) any 
 *  later version.
 *
 *  The stream.ai library (and its submodules) is distributed in the hope
 *  that it will be useful, but WITHOUT ANY WARRANTY; without even the implied 
 *  warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package stream.io;

import java.io.InputStream;
import java.io.Serializable;
import java.net.URL;

import net.minidev.json.JSONObject;
import net.minidev.json.parser.JSONParser;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import stream.annotations.Description;
import stream.data.Data;
import stream.data.DataFactory;

/**
 * @author Christian Bockermann <[email protected]>
 * 
 */
@Description(group = "Data Stream.Sources")
public class JSONStream extends AbstractDataStream {

	static Logger log = LoggerFactory.getLogger(JSONStream.class);
	JSONParser parser = new JSONParser(JSONParser.DEFAULT_PERMISSIVE_MODE);

	/**
	 * @param in
	 * @throws Exception
	 */
	public JSONStream(InputStream in) throws Exception {
		super(in);
	}

	public JSONStream(URL url) throws Exception {
		super(url);
	}

	public JSONStream(URL url, String user, String password) throws Exception {
		super(url, user, password);
	}

	/**
	 * @see stream.io.DataStream#close()
	 */
	@Override
	public void close() {
	}

	/**
	 * @see stream.io.AbstractDataStream#readHeader()
	 */
	@Override
	public void readHeader() throws Exception {
	}

	/**
	 * @see stream.io.AbstractDataStream#readItem(stream.data.Data)
	 */
	@Override
	public Data readItem(Data instance) throws Exception {

		if (instance == null)
			instance = DataFactory.create();

		if (reader == null)
			this.initReader();

		String line = reader.readLine();
		log.debug("line: {}", line);
		if (line == null) {
			return null;
		}

		log.debug("Parsing item from {}", line);
		JSONObject object = parser.parse(line, JSONObject.class);
		if (object != null) {
			for (String key : object.keySet()) {
				Object val = object.get(key);
				if (val instanceof Serializable)
					instance.put(key, (Serializable) val);
				else
					instance.put(key, val.toString());
			}
		} else {
			log.debug("Failed to parse item, object = {}", object);
		}

		log.debug("returning instance: {}", instance);
		return instance;
	}
}